Conventionally, in order to shield a magnetic field, there has been proposed a magnetic shield room which prevents leakage of a magnetic field generated in a magnetic field generation source to outside, by covering the magnetic field generation source. This magnetic shield room is put in practical use as a room (hereinafter, “MRI room”) in which an MRI (Magnetic Resonance Imaging) device used in medical facilities is installed, for example. Broadly, this magnetic shield room is configured by having a magnetic material embedded in all or a part of a wall, a ceiling, and a floor. Leakage of a magnetic field to outside is prevented by having a magnetic flux reaching the wall, the ceiling, and the floor bypassed via the magnetic material.
Because this magnetic shield room surrounds the magnetic field generation source with the wall, the ceiling, and the floor, an internal space of the magnetic shield room is closed hermetically, and this gives a feeling of pressure to a person entering the room. In order to resolve this problem, configuring a magnetic shield room using an open magnetic shield body is proposed (see, for example, Patent Document 1). This open magnetic shield body is configured by having plural cylindrical bodies supported with a frame. According to this configuration, the inside and outside of the magnetic shield room are visually open via the internal space of the cylindrical bodies. Therefore, a feeling of pressure to a person entering the room can be decreased.
However, because the magnetic shield body in Patent Document 1 has plural cylindrical bodies linearly contacted to each other, there is a problem that stress concentration is generated in these contact portions. In order to solve this problem, inventors of the present invention proposed a magnetic shield body configured by having plural cylindrical bodies arranged in a non-contact shape with a mutual interval between the cylindrical bodies (Patent Document 2, not published at the time of filing the present application). According to this configuration, a stress load to the cylindrical bodies can be decreased, and assembly and disassembly of the magnetic shield body are facilitated.    Patent Document 1: Japanese Patent Application Laid-open No. H6-13781    Patent Document 2: Japanese Patent No. 2006-350064